Date Full Report Received


Date Abstract Report Received



Primary Investigator:
Sow housing has become a very controversial welfare issue for pork producers. We cannot justify implementing alternative housing systems without concrete scientific data from these system that provide for improved sow well-being. Therefore the specific objectives of this project were to: 1) design a housing system that can be retro-fitted to provide the same animal capacity in existing housing facilities, yet constructed so as to allow flexibility in stall dimensions to address welfare issues of physical size of the stall, the freedom of sows to move, and to socialize (if important to sow) and 2) to assess the practicality of these systems and the impact on sow welfare using an integrative approach. Based on results of this study, the long term objective is to design, optimize and implement sow housing and management systems that will enhance sow well-being while sustaining the productivity and profitability of swine production. Ninety-six multi-parous crossbred Yorkshire sows were allotted to either a modified gestation stall (FLEX) that allows the expansion of the width of the stall, the free access stall-pen which gives sows the option to be in a group pen or individual stall (FREE), or a standard non-adjustable stall which was used as a control (STALL). On d 89 of gestation, the width of the FLEX was increased to provide the sow an additional 7-8 cm of space. Sow performance and productivity measures were collected along with behavioral and physiological measures throughout gestation. Data were analyzed using Proc MIXED with repeated measures and Proc CORR (SAS software).

Comparing alternative housing systems (FLEX and FREE) with STALL multiple performance characteristics were affected. Sow body wounds and swelling were greater amongst sows kept in FREE compared with sows kept in either STALL or FLEX, however as day of gestation progressed the severity and frequency of body wounds and swelling for sows kept in FREE decreased, but continued to remain higher than sows kept in either of the individual stall type. Conversely, sows kept in FLEX had greater front leg swelling than sows kept in STALL, while sows kept in FREE had greater hind leg swelling than did sows kept in either individual stall type. Sows kept in STALL had greater wounds or lesions on the ears than did sows kept in FLEX or FREE. Additionally sows kept in FREE also had greater mean BW, back-fat depth, and BCS than did sows kept in STALL or FLEX. Endocrine and immune responses were influenced by alternative housing types; with those sows kept in FREE having greater neutrophil and lymphocyte counts, as well as plasma cortisol levels, but lower percentages of eosinophils compared with sows kept in either STALL or FLEX. Sows kept in STALL had greater total WBC count than sows in FLEX and greater T-lymphocyte proliferation than sows kept in either FLEX or FREE. Twenty-four hours after expanding the width of the FLEX (7 to 8cm), sows in those stalls had an increase in lymphocyte counts and greater total WBC count, while neutrophil chemotaxis decreased when compared with their sample prior to the expansion of the stall. Postural, maintenance, and oral-nasal-facial (ONF) behaviors were also influenced by housing type. Postural change—from laying to standing and vice-versa were greater for sows kept in FLEX than for those sows kept in either STALL or FREE. Sows kept in STALL had longer drink durations than did sows in both FLEX and FREE, but have less frequent bouts of eating than sows kept in FREE. Sows kept in FLEX performed significantly more frequent and longer duration of sham-chew bouts than did sows kept in either STALL or FREE.

When assessing the impact that social status has on space utilization and general behaviors of sows kept in FREE system, we found that submissive sows have greater duration of sitting bouts than did dominant sows; while dominant sows perform more eat bouts and have longer durations of drink than submissive sows. Dominant sows also performed more sham-chew behavior than did submissive sows. When given the choice to utilize a group pen or an individual stall, dominant sows (70-80%) use the group-pen area more than submissive sows (40-50%). However, day of gestation also influenced utilization of group-pen area across social ranks. On d30 (day of allotment) dominant sows (70%) used the group-pen area more than submissive sows (18%), through mid-gestation dominant sows still utilized the group-pen area more than submissive sows, but submissive sows did use pen area more than they did on d30. However as day of gestation increased (closer to parturition), submissive sows began to utilize the individual stalls more, while dominant sows percentage of time (70-80%) in group-pen area stayed consistent throughout gestation.

The results of the study reported within indicate that sow performance, productivity, immune status, and behavior were influenced by alternative individual housing systems (FLEX), as well as a combination of both individual stall and group-pen area (FREE). Allowing researchers to identify which concepts or components of each alternative accommodations (FLEX (expanding width) or FREE (stall or group pen preference)) improve well-being and therefore should be used to optimize a housing system for gestating sows.

When comparing two alternative housing systems to a standard gestation stall, results suggest that lesions/wounds, swelling, and behavior are more affected by housing design than either performance traits or endocrine and immune responses, biologically. However, the physical, biological, and social components within each alternative system may be imposing more of a response than the housing system itself. For example, sows kept in a FLEX stall change postures (stand, sit, lay) significantly more than did sows kept in either FREE or STALL, Furthermore, other oral activity (sham-chew) was also increased amongst sows kept in FLEX before, during, and after feeding than sows in other treatments. We hypothesize this increase in sham-chew behavior and postural changes around feeding could be due to limited ability to perform ONF behavior, since all bar-direction on the FLEX system are vertical. When expanding the stall an additional 7-8 cm late in gestation can influence an immune response. An increase in total WBC and lymphocyte counts could suggest an acute immune response occurred, however the significant decrease in neutrophil chemotaxis implies that there was more likely a shift in the immune system. Nevertheless, finding that expanding the width of stalls does influence indicators of well-being, causes us to hypothesize that correcting the front gate of the FLEX stall, to allow or encourage bar-biting or ONF behavior, could increase the immune benefits of expanding the stall even more so, resulting in overall improved well-being. When comparing the FREE system to the standard gestation STALL few biologically relevant results were reported. Lesions were found to be significantly greater amongst sows kept in FREE compared to sows kept in either of the individual stall types, however this increase in lesions/wounds did not seem to influence other indicators of well-being. Sow BW, BF, and BCS may have been statistically different, however biologically not relevant as indicators of improved well-being. Results pertaining to sow social status on behavior and space utilization within FREE indicate that dominance status has a major impact on how and when sows prefer to spend their time, as well as, where they choose to spend the majority of their time when given the opportunity to choose between individual stalls and a group pen. Since, few biological differences were found when comparing sows kept in either FLEX or FREE to sows kept in STALL, we hypothesize that industry standards of well-being exist across various sow housing systems and that physical, biological, and social components within existing housing systems may influence well-being more hence that upon refining these various components all of these systems could be acceptable alternative systems.